VMware CTO looks back at 'wild ride'

Network World - Few IT companies have fundamentally changed the data center like VMware. Yet 13 years into VMware's existence nearly all of its co-founders, including the wife-and-husband team of CEO Diane Greene and Chief Scientist Mendel Rosenblum, have moved on.

Still left to tell the story of VMware's early days is Stephen Herrod, the chief technology officer, who was working with Rosenblum as a Ph.D. student at Stanford University before VMware's founding in 1998.

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At the time, there was little reason to think the idea of applying IBM's mainframe virtualization to commodity x86 servers would transform enterprise IT and be used by nearly every member of the Fortune 1000.

"I guess you have to be blindly optimistic to do any of this," Herrod said in an interview with Network World. "At the time, no one had ever virtualized the Intel processor and it became clear very quickly that it was not designed to do so. There were a lot of hard technical challenges that made it fun."

There were five co-founders of VMware. Although Herrod wasn't one of the five they were his office mates at Stanford, where a graduate school project laid the foundation for VMware's technology.

IBM created virtualization in the 1960s to enable more efficient use of mainframes, but the x86 servers with Intel and AMD chips so common in today's data centers never gained the benefits of a hypervisor until Rosenblum and his students started their work.

Although it was virtualizing Windows Server that would make VMware its real cash, the first step was getting the Windows desktop to run in a virtual machine. It took two hours to get Windows 95 to boot in a VM, but the fact that it booted at all made the project a success.

"That was a huge victory, because the team figured out how to make virtualization boot," Herrod says.

While the Windows desktop OS served as an important test case, and VMware's first product was focused on the desktop, Herrod says "the plan all along was definitely to bring virtualization into the data center and onto servers."

At Stanford, the team first worked on virtualizing the MIPS architecture as a proof of concept, but VMware's focus would be Intel chips. The first challenge was making an operating system feel at home in a virtual machine on an Intel processor, by emulating the whole PC within the VM, letting the OS believe it has access to a full computer including the CPU, graphics card and disk drive. The second challenge was being able to emulate the Intel architecture at high speed.